(CNN) - In a hotly contested ballot measure, voters in Maine said yes to same-sex marriage, CNN projects, becoming the first state to approve the freedom to marry for same-sex couples through a majority vote on a ballot measure. A number of states already allow gay marriage, but those laws were accomplished through court rulings or with the help of legislation.

One leading advocacy group, Freedom to Marry, said Maine is expected to begin issuing marriage licenses in mid-December.

Maine was one of four states with a same-sex marriage initiative.

"Now the commitment gay and lesbian couples have made in life will be respected equally under the law, celebrated before their loved ones, and called what it is: marriage," said Marc Solomon, Freedom to Marry National Campaign Director in a news release. "It's hard to overstate the national significance of this vote," he added.